The invention relates to the design and operation of gaseous reactor vessels for producing epilayers on a substrate.
Organometallic vapor phase epitaxy (OMVPE) is used to grow multilayer semiconductor structures for a variety of electronic and optoelectronic applications such as quantum well and super lattice devices. For many of these applications, the epilayers must be laterally uniform and the interfaces between successive epilayers, micro thin additive layers of different alloys, should be as abrupt as possible. To obtain abrupt interfaces with OMVPE, stepwise changes are made in the composition of the gas stream injected into the reactor. Consequently, epilayer quality is limited by gas dynamics. Optimization of the OMVPE process promises significant advantages over molecular beam epitaxy which, although presently offering more precise control, is by its nature slow, expensive, difficult to maintain and limited to a single wafer at-a-time. For certain applications practical mass production using OMVPE demands a higher degree of epilayer uniformity over a larger area with interface widths of at most a few monolayers.
While designed principally for OMVPE, several of the optimization techniques described below are applicable to other thin film technologies such as chemical vapor deposition.